Formation of edge misfit dislocations in Ge_xSi_(1-x) (x～0.4-0.5) films grown on misoriented (001)→(111) Si substrates

摘要

We have studied the dislocation structure at the initial stage of relaxation of Ge_xSi_(1-x) films (x～0.4-0.5) grown on Si substrates tilted 6° about the <011 > axis. It is demonstrated that edge misfit dislocations (MDs) in the miscut direction arise in the form of short segments on intersections of 60° MDs, As a result, the total length of the edge MDs in the direction of substrate misorientation becomes substantially smaller than that in the direction of the miscut axis. Substrate misorientation from the singular plane made it possible to discover the MD configurations consisting of a short segment of an edge MD and only two 60° MDs diverging from this segment in the miscut direction. This configuration is assumed to start forming from simultaneous nucleation of two dislocation half-loops, which form a short edge MD in the interface and then propagate in only one direction in the form of two diverging branches of 60° MDs.